Stroke continues to be the number three principal cause of death, and one of the leading causes of disability, in the United States. Continued improvements in these statistics requires a better understanding of the functional dynamics of the cerebral vasculature and oxygen utilization of the surrounding tissue during various physiological conditions.We propose a computerized method that affords real time continuous noninvasive measurement and quantitative analysis of the combined hemoglobin saturation levels and auditory evoked potentials during ischemic conditions of the brain. Unique enhancements of the current Near Infrared Spectroscopy (NIRS) technology have been developed along with a Brain Auditory Evoked Potential (BAEP) system. In Phase I we will demonstrate the feasibility of such an undertaking with animal experiments designed to investigate the capabilities of the novel NIRS system coupled with the BAEPs generated during varying extents of cerebral ischemia. In Phase II, we will extend this application to further investigate conditions of cerebral ischemia as well as hypoxic states. The long-term goal is to provide a real time noninvasive monitoring capability of brain oxygenation during surgical procedures and cerebral vascular accidents.